Tube bender

ABSTRACT

A manually operable tube bender wherein a straight tube is inserted between a mandrel and a bending shoe with the bending shoe being swung about the axis of the mandrel groove to progressively bend the tube into the groove. A hook is provided for preventing longitudinal movement of the tube as a result of the friction forces generated by the sliding of the hook against the tube as it is bent. A number of different forms of such hooks are disclosed for providing improved tube retention.

1451 Aug. 7. 1973 United States Patent [191 Kowal et al.

[ TUBE BENDER Lundis 72/460 2/1933 Lidseen.................. 72/159 .w v8 D 7 6 9 H .1 38 9 09 31 1 .w e e Hk mm W. sm mG m d oa KS k mm n h h wn LWo r o t n e V n I M 7 1 [73] Assignee: Imperial-Eastman Corporation,Examinercharles Lanham Chica o, [11, Assistant ExaminerM. .I. KeenanAttorneyHofgren, Wegner, Allen, Stellman & McCord [22] Filed: Sept. 28,1971 [21] Appl. No.: 184,567

[57] ABSTRACT A manually operable tube bender wherein a straight tube isinserted between a mandrel and a bending shoe with the bending shoebeing swung about the axis of the mandrel groove to progressively bendthe tube into the cove. A hook is provided for preventing longitudinalmovement of the tube as a result of the friction forces generated by thesliding of the hook against the tube as r g 98 8 SW38 M34 1 7, WW ,1 M 75, 1 24.4 2 7 I 9129 91 l 3 d ,1 .e B "4 C mum mmms c u 4 n n. e 2 u ""1"mh h mum R "8 flu L C smm I i UmF 12 l 2 8 6 555 5 [1.1. .l

UNTED STATES PATENTS it is bent. A number of different forms of suchhooks are disclosed for providing improved tube retention.

72/459 18 Clnlma, 10 Drawlng Figures 2,927,490 3/1960 2,709,382 5/1955Safranski 1,835,264 12/1931 PATENTED AUG 7 i975 lnvenib rs:- Z eonardJKO wal, SaddZev;

TUBE BENDER BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to tube benders and in particular to hand operatedtube benders wherein the tube is held by a hook member during the tubebending operation.

2. Description of the Prior Art In the conventional hand operated tubebender, a mandrel is provided with a peripheral groove. A bending shoeis swingably associated with the mandrel to move around the periphery ofthe mandrel and urge a tube progressively into the mandrel groove toeffect a desired bend therein.

To prevent longitudinal movement of the tube during the bendingoperation, which may occur as the result of friction forces generated bythe shoe as it moves along the tube surface in effecting the bend, hookor clamp means have been provided. In one improved form of such a tubebender, such as shown in Philippe U.S. Pat. No. 2,796,785, issued June25, 1957 for a Tube Bender, a hook 14 is provided on the handle 13 topivot about an axis perpendicular to the axis of the mandrel groove.Thus, in use of the tube bender thereof, the user inserts the tube to bebent between the shoe and the mandrel and pivotally swings the hook intotube-engaging disposition.

In the concurrently issued patent to Kowal et al., U.S. Pat. No.2,796,784, issued June 25, 1957 for a Tube Bender, a modified form ofsuch tube bender is shown to include a hook having a wedge element 16associated therewith for locking the tube more firmly to the hook duringthe bending operation.

In Franck U.S. Pat. No. 2,979,976, issued Apr. 18, 1961 for a Plier-TypeTube Bending Tool, the hook is shown to be pivotally mounted to themandrel for pivoting it about an axis perpendicular to the mandrel axis.

In the conventional hook construction, the portion of the hook engagingthe tube is made to be arcuate in general conformity of the shape of thetube to be bent, as illustrated in the above-indicated prior artpatents.

SUMMARY OF THE INVENTION The present invention comprehends an improvedtube bender wherein the hook is provided with a straight edge forimproved coaction with the tube to be bent. The invention comprehendsthat the mandrel may be provided with a plurality of axially spacedcoaxial grooves for use in bending different size tubes. Alternatively,the invention comprehends providing a mandrel with a single bendinggroove adapted for bending different size tubes by means of the straighthook edge. The mandrel may be provided with suitable scale markingscorresponding to the different size tubes for use in controlling thedesired angular extent of the bend with the different size tubes.

The straight edged hook may be fixedly associated with themandrel-handle structure, and in the illustrated embodiment, comprisesan integral extension thereof.

In a modified form, the straight edged hook is adapted to swing about anaxis parallel to the mandrel axis with the swinging movement limited inthe direction of urging of the tube by the shoe during the bendingoperation, by means of a stop fixedly associated with the handle andmandrel.

In a further modified form of the invention, the hook is slidable in asuitable recess between a retracted position permitting the tube to beinstalled between the mandrel and shoe in the bend-start arrangement,and an operative position wherein the hook engages the tube to preventlongitudinal movement thereof during the bending operation. The hook maybe resiliently p0- sitioned in the tube "bender, and in the illustratedembodiment, is biased to the tube-engaging position.

In each of the different forms, the hook is provided with a tube-holdingrear edge portion adapted to en gage an outer portion of the tube toeffect the desired retention thereof against longitudinal movementduring the bending operation.

BRIEF DESCRIPTION OF THE DRAWING Other features and advantages of theinvention will be apparent from the following description taken inconnection with the accompanying drawing wherein:

FIG. 1 is a side elevation of a tube bender provided with a hookstructure embodying the invention;

FIG. 2 is a broken end view thereof;

FIG. 3 is a fragmentary end view looking in a direction opposite to thatof FIG. 2 and with the shoe omitted to facilitate illustration of theremaining structure;

FIG. 4 is a fragmentary horizontal section taken substantially along theline 4-4 of FIG. 1;

FIG. 5 is a fragmentary end elevation of a modified form of tube benderembodying the invention;

FIG. 6 is a fragmentary side elevation of the mandrel element of thetube bender of FIG. 5;

FIG. 7 is a fragmentary end elevation of a further modified form of tubebender embodying the invention;

FIG. 8 is a fragmentary side elevation of the tube bender of FIG. 7;

FIG. 9 is a fragmentary side elevation of a further modified form oftube bender embodying the invention; and

FIG. 10 is a fragmentary end elevation thereof with a portion shown insection to facilitate the illustration of the hook structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the exemplary embodiment ofthe invention as disclosed in FIGS. l4 of the drawing, a tube bendergenerally designated 10 is shown to comprise a mandrel l 1 having aperipheral tube bending groove 12 in which a tube T is bent by means ofa shoe 13 swingable about the axis 14 of the mandrel groove by means ofa connecting link 15 pivotally connected to the mandrel by a pivot 16and to the shoe by a pivot 17. A handle 18 is connected to shoe l3 and ahandle 19 is connected to mandrel 11 for suitable manipulation of thetool to effect a hand operation thereof in bending the tube T to adesired angularity, as illustrated in FIG. 1.

Handle 18 is provided with a stop pin 20 adapted to abut against ashoulder portion 21 of the connecting link 15 when the shoe is in thetube-bending position of FIG. 1. Swinging of the handle in acounterclockwise direction from the position of FIG. 1 permits adisplacement of the shoe 13 from the tube-engaging position forfacilitated installation of the tube T between the mandrel and shoe inplacing the tube in the tool at the initiation of the tube-bendingoperation.

The invention comprehends providing an improved hook means generallydesignated 22 in the tool for improved facility in bending of the tubeT. As shown in FIG. 2, hook means 22 defines a hook having a straighttube-engaging portion 23 aligned with the mandrel groove 12 for holdingthe tube T against longitudinal movement as the shoe 13 is swung in aclockwise direction (see FIG. 1) from a bend-start point 24. Thetubeholding portion includes a leading edge 25 adapted to be urged intothe outer portion of the tube as a result of the friction forces of theshoe urging the tube forcibly against the hook edge 25, as illustratedin FIG. 1.

Mandrel ll may be provided with a plurality of tubebending grooves.Thus, as shown in FIG. 2, groove 26 and groove 27 may be provided inaddition to groove 12 accommodating tubes of successively smallerdiameter whereby the tool is adapted to bend different size tubes bysuitable placement thereof in the corresponding mandrel groove and withthe tube engaging the hook edge portion 25 similarly in each instance.The mandrel grooves 12, 26 and 27 are coaxially disposed on the mandrelin spaced axial relationship so that the bending operation is similar ineach instance.

It has been found that with the use of the straight edge hook 22, amandrel having three grooves, such as grooves 12, 26 and 27, mayaccommodate the entire range of conventional tube sizes from underonesixteenth inch up to one-fourth inch where the grooves have radii asfollows: groove 12 approximately 0.125 inch to 0.127 inch; groove 26approximately 0.093 inch to 0.095 inch; and groove 27 approximately0.062 inch to 0.064 inch. The inner radius of groove 12 relative to themandrel axis may be approximately 0.435 inch, the inner radius of thegroove 26 to the mandrel may be approximately 0.498 inch, and the innerradius of groove 27 to the mandrel may be approximately 0.560 inch. Theinner edge 25 of the hook may be spaced from a line perpendicular to thehandle 19 through the mandrel axis 14 approximately 0.685 inch and thehook may have a width of approximately seven-sixteenths inch, i.e.,parallel to the tube T, as shown in FIG. 1.

By virtue of the fact that the tube may swing somewhat about its contactpoint with the mandrel in the bending groove depending on thecross-sectional diameter of the tube, the tool 10 is adapted toaccommodate in each of the grooves, tubing having smaller crosssectionsthan that for which the groove is specifically designed. Thus, asillustrated in FIGS. 5 and 6, where a substantially smaller diametertube is inserted in the mandrel groove 12, the tube assumes a positionrelative to the mandrel wherein the tube T becomes tangent to the groove12 at a point 28 spaced angularly from the bend-start point 24 a smalldistance resulting from the elevation of the lefthand end of the tube T'into abutment with the hook edge 25 rearwardly of the bendstart point.Thus, the scale means 29 of the tool 10, as shown in FIG. 1, isaugmented by a supplementary scale means 30 displaced angularly fromscale means 29 throughout an amount equal to the spacing of bendstartpoint 28 from bend-start point 24. Where the tube has only a slightlysmaller diameter than that of the groove, the scale markings 29 may beutilized by the user making only a slight compensatory adjustment in theposition of the shoe at the end of the bend, i.e., positioning the shoeslightly beyond the angular marking desired. Thus, as discussed above,the multiple groove mandrel 11 may be utilized to accommodate a widerange of different diameter tubes with the three mandrel groovesthereof.

Turning now to FIGS. 7 and 8, a further modified form of tube benderembodying the invention is shown to comprise a tube bender generallydesignated I10 generally similar to tube bender 10 but having a straightedge hook 122 pivotally mounted to the handle ll9-mandrel lll structureby means of a pivot 13] having its axis 132 parallel to the axis 114 ofthe mandrel. A stop 133 is provided on the handle ll9-mandrel lllstructure for limiting the pivotal swing of the hook in a forwarddirection, i.e., clockwise as seen in FIG. 8, thereby to cause leadingedge 125 to retain the tube against longitudinal movement in the samemanner as effected by edge 25 of hook 22 in tool 10 in the bendingoperation.

As will be understood by those skilled in the art, the hook 122 may bepivotally mounted in the tool to swing about an axis perpendicular tothe mandrel axis in the conventional manner with the straight edgeportion 125 cooperating with the tubing during the bending operation inthe improved manner of hook 22 of tool 10.

As shown in FIGS. 9 and 10, a further modified form of tube bendergenerally designated 210 is shown to comprise a straight edge hook 222comprising a block mounted in an extension 234 of the handle-mandrelstructure forselective positioning for engagement with the tube, or in aretracted disposition in the support 234 permitting facilitated mountingof the tube in the too]. As shown, the block 222 is slidably received ina corresponding square bore 235 in extension 234 and is biased intooverlying association relative to the tube by a coil spring 236 receivedbetween an inturned shoulder 237 on the extension 234 and the inner endof the block 222. A retainer rod 238 extends outwardly from the innerend of the block 222 through the outer end of the bore 235 and isprovided at its outer end with a finger manipulating button 239 forselectively retracting the block against the biasing action of thespring 236. Block 222 defines a tube-retaining edge 225 which functionssimilarly to edge 25 of hook 22 in tool 10 to retain the tube againstlongitudinal movement during the bending operation. Edge 225 comprises astraight edge similar to straight edge 25 of the tools illustrated inFIGS. 1-6 and the edge 125 of the tool 110, in providing the improvedtube-holding functioning discussed above. As will be obvious to thoseskilled in the art, the block 222 may be elongated and the mandrel 211of the tool 210 may be provided with a plurality of different sizegrooves in conformity with the structural concepts embodied in mandrels11 and 111 within the scope of the invention. In each case, use of thestraight groove permits a range of tube sizes to be bent in the tubebender to provide further improved tube-holding action. The stop 133 maybe omitted in the tool permitting the hook 122 to swing sufficiently toabut any size tube being bent in the tool. Thus, the inventive conceptsembodied in the different illustrative embodiments provides an improvedtube-bending function by extremely simple and economical means.

The foregoing disclosure of specific embodiments is illustrative of thebroad inventive concepts comprehended by the invention.

We claim:

1. In a hand tube bender having a mandrel provided with a peripheraltube-bending groove extending about a mandrel axis and defining abend-start point at one end, a handle connected to said mandrel, abending shoe, and means for swinging the bending shoe coaxiallycircumjacent said mandrel groove from adjacent said bend-start point ina forward direction away therefrom with a tube to be bent receivedtherebetween, improved means for retaining the tube to be benttherebetween against axial displacement during a tube-bending operationcomprising: a hook disposed rearwardly adjacent said bend-start pointhaving a straight, planar tube-holding surface extending parallel to themandrel groove disposed to engage an outer portion of the tube spacedfrom the mandrel groove rearwardly of the bend-start point to precluderadial constrictive clamping of the tube in the mandrel groove while yetholding the tube against longitudinal movement while the shoe is swungagainst the outer portion of the tube from said bend-start pointforwardly thereof to press the tube into the mandrel groove and therebyform a desired bend therein.

2. The tube bender means of claim 1 wherein said hook is fixedlyconnected to said handle.

3. The tube bender means of claim 1 wherein said mandrel is providedwith a plurality of different coaxial size bending grooves in axialside-by-side relationship spaced from said mandrel axis differentdistances preselected so that the outer portion of each tube receivedtherein having an outer diameter corresponding to the size of the grooveis spaced from said mandrel axis at the bend-start point the samedistance whereby each tube engages the straight tube-holding surfacesimilarly.

4. The tube bender means of claim 1 wherein said mandrel is providedwith a plurality of different coaxial size bending grooves in axialside-by-side relationship spaced from said mandrel axis differentdistances preselected so that the outer portion of each tube receivedtherein having an outer diameter corresponding to the size of the grooveis spaced from said mandrel axis at the bend-start point the samedistance whereby each tube engages the straight tube-holding surfacesimilarly, and said shoe is provided with a plurality of tubeengaginggrooved surfaces aligned with the respective mandrel grooves, each shoegroove having a size corresponding to the confronting mandrel groove,the outer portion of each shoe groove being aligned with said straighttube-holding surface when the shoe is disposed at the bend-startposition.

5. The tube bender means of claim 1 including means for pivotallymounting the hook to swing about an axis parallel to the mandrel axisand means for limiting the forward swinging movement to a preselectedposition when the hook holdingly engages the outer portion of the tube.

6 The tube bender means of claim 1 including means for pivotallymounting the hook to swing about an axis parallel to the mandrel axisand a stop shoulder on said connected mandrel and handle structure forlimiting the forward swinging movement to a preselected position whenthe hook holdingly engages the outer portion of the tube.

7 The .tube bender means of claim 1 wherein said hook comprises anintegral extension of said handle.

.8. In a hand tube bender having a mandrel provided with a peripheraltube-bending groove extending about a mandrelaxis and defining a firstbend-start point at one .end, a handle connected to said mandrel, abending shoe, and means for swinging the bending shoe coaxiallycircumjacent said mandrel groove from adjacent said bend-start point ina forward direction away therefrom with a tube to be bent receivedtherebetween, improved means for retaining the tube to be benttherebetween against axial displacement during a tube-bending operationcomprising: a hook disposed rearwardly adjacent said bend-start pointhaving a straight, planar tube-holding surface extending parallel to themandrel groove disposed to engage an outer portion of the tube spacedfrom the mandrel groove rearwardly of the bend-start point to precluderadial constrictive clamping of the tube in the mandrel groove while yetholding the tube against longitudinal movement while the shoe is swungagainst the outer portion of the tube from said bend-start pointforwardly thereof to press the tube into the mandrel groove and therebyform a desired bend therein; and scale means on the mandrel indicatingsaid bend-start point and a second, displaced bendstart point correlatedwith the position assumed by a tube having a smaller diameter than thatof a full size tube to be bent by said tool as a result of an angularshift of the smaller diameter tube in extending rectilinearly betweensaid hook and the mandrel groove.

9. The tube bender means of claim 8 wherein said scale means includesfirst bend-finish indicia corresponding to different angular degreebends from said bend-start point and second bend-finish indiciadisplaced similarly as said second bend-start point for indicatingdifferent angular bends of the smaller diameter tube.

10. In a hand tube bender having a mandrel provided with a peripheraltube-bending groove extending about a mandrel axis and defining abend-start point at one end, a handle connected to said mandrel, abending shoe, and means for swinging the bending shoe coaxiallycircumjacent said mandrel groove from adjacent said bend-start point ina forward direction away therefrom with a tube to be bent receivedtherebetween, improved means for retaining the tube to be benttherebetween against axial displacement during a tube-bending operationcomprising: a hook disposed rearwardly adjacent said bend-start pointhaving a straight, planar tube-holding surface extending parallel to themandrel groove disposed to engage an outer portion of the tube spacedfrom the mandrel groove rearwardly of the bend-start point to precluderadial constrictive clamping of the tube in the mandrel groove while yetholding the tube against longitudinal movement while the shoe is swungagainst the outer portion of the tube from said bend-start pointforwardly thereof to press the tube into the mandrel groove and therebyfonn a desired bend therein; and means for guiding said hook in arectilinear path parallel to said mandrel axis selectively to and from aposition wherein the hook engages the tube at said portion rearwardly ofthe bend-start point.

11. The tube bender means of claim 10 wherein said hook comprises aslide block, said tube bender includes support means connected to saidhandle and having a recess slidably receiving said slide block, andmeans for selectively retracting said slide block to permit placement ofsaid tube in position in the tube bender without interference by saidhook slide block.

12. The tube bender means of claim 10 further including means forbiasing said hook to the tubeengaging position.

13. The tube bender means of claim 10 wherein said hook comprises aslide block, said tube bender includes support means connected to saidhandle and having a recess slidably receiving said slide block, andmeans for selectively retracting said slide block to permit placement ofsaid tube in position in the tube bender without interference by saidhook slide block, and means for biasing said slide block to thetube-engaging position.

14. The tube bender means of claim 10 wherein said recess and slideblock are polyhedral in cross-section.

15. The tube bender means of claim 10 including

1. In a hand tube bender having a mandrel provided with a peripheraltube-bending groove extending about a mandrel axis and defining abend-start point at one end, a handle connected to said mandrel, abending shoe, and means for swinging the bending shoe coaxiallycircumjacent said mandrel groove from adjacent said bend-start point ina forward direction away therefrom with a tube to be bent receivedtherebetween, improved means for retaining the tube to be benttherebetween against axial displacement during a tube-bending operationcomprising: a hook disposed rearwardly adjacent said bend-start pointhaving a straight, planar tube-holding surface extending parallel to themandrel groove disposed to engage an outer portion of the tube spacedfrom the mandrel groove rearwardly of the bend-start point to precluderadial constrictive clamping of the tube in the mandrel groove while yetholding the tube against longitudinal movement while the shoe is swungagainst the outer portion of the tube from said bend-start pointforwardly thereof to press the tube into the mandrel groove and therebyform a desired bend therein.
 2. The tube bender means of claim 1 whereinsaid hook is fixedly connected to said handle.
 3. The tube bender meansof claim 1 wherein said mandrel is provided with a plurality ofdifferent coaxial size bending grooves in axial side-by-siderelationship spaced from said mandrel axis different distancespreselected so that the Outer portion of each tube received thereinhaving an outer diameter corresponding to the size of the groove isspaced from said mandrel axis at the bend-start point the same distancewhereby each tube engages the straight tube-holding surface similarly.4. The tube bender means of claim 1 wherein said mandrel is providedwith a plurality of different coaxial size bending grooves in axialside-by-side relationship spaced from said mandrel axis differentdistances preselected so that the outer portion of each tube receivedtherein having an outer diameter corresponding to the size of the grooveis spaced from said mandrel axis at the bend-start point the samedistance whereby each tube engages the straight tube-holding surfacesimilarly, and said shoe is provided with a plurality of tube-engaginggrooved surfaces aligned with the respective mandrel grooves, each shoegroove having a size corresponding to the confronting mandrel groove,the outer portion of each shoe groove being aligned with said straighttube-holding surface when the shoe is disposed at the bend-startposition.
 5. The tube bender means of claim 1 including means forpivotally mounting the hook to swing about an axis parallel to themandrel axis and means for limiting the forward swinging movement to apreselected position when the hook holdingly engages the outer portionof the tube.
 6. The tube bender means of claim 1 including means forpivotally mounting the hook to swing about an axis parallel to themandrel axis and a stop shoulder on said connected mandrel and handlestructure for limiting the forward swinging movement to a preselectedposition when the hook holdingly engages the outer portion of the tube.7. The tube bender means of claim 1 wherein said hook comprises anintegral extension of said handle.
 8. In a hand tube bender having amandrel provided with a peripheral tube-bending groove extending about amandrel axis and defining a first bend-start point at one end, a handleconnected to said mandrel, a bending shoe, and means for swinging thebending shoe coaxially circumjacent said mandrel groove from adjacentsaid bend-start point in a forward direction away therefrom with a tubeto be bent received therebetween, improved means for retaining the tubeto be bent therebetween against axial displacement during a tube-bendingoperation comprising: a hook disposed rearwardly adjacent saidbend-start point having a straight, planar tube-holding surfaceextending parallel to the mandrel groove disposed to engage an outerportion of the tube spaced from the mandrel groove rearwardly of thebend-start point to preclude radial constrictive clamping of the tube inthe mandrel groove while yet holding the tube against longitudinalmovement while the shoe is swung against the outer portion of the tubefrom said bend-start point forwardly thereof to press the tube into themandrel groove and thereby form a desired bend therein; and scale meanson the mandrel indicating said bend-start point and a second, displacedbend-start point correlated with the position assumed by a tube having asmaller diameter than that of a full size tube to be bent by said toolas a result of an angular shift of the smaller diameter tube inextending rectilinearly between said hook and the mandrel groove.
 9. Thetube bender means of claim 8 wherein said scale means includes firstbend-finish indicia corresponding to different angular degree bends fromsaid bend-start point and second bend-finish indicia displaced similarlyas said second bend-start point for indicating different angular bendsof the smaller diameter tube.
 10. In a hand tube bender having a mandrelprovided with a peripheral tube-bending groove extending about a mandrelaxis and defining a bend-start point at one end, a handle connected tosaid mandrel, a bending shoe, and means for swinging the bending shoecoaxially circumjacent said mandrel groove from adjacent said bend-startpoint in a forward direction away therefrom with a tube to be bEntreceived therebetween, improved means for retaining the tube to be benttherebetween against axial displacement during a tube-bending operationcomprising: a hook disposed rearwardly adjacent said bend-start pointhaving a straight, planar tube-holding surface extending parallel to themandrel groove disposed to engage an outer portion of the tube spacedfrom the mandrel groove rearwardly of the bend-start point to precluderadial constrictive clamping of the tube in the mandrel groove while yetholding the tube against longitudinal movement while the shoe is swungagainst the outer portion of the tube from said bend-start pointforwardly thereof to press the tube into the mandrel groove and therebyform a desired bend therein; and means for guiding said hook in arectilinear path parallel to said mandrel axis selectively to and from aposition wherein the hook engages the tube at said portion rearwardly ofthe bend-start point.
 11. The tube bender means of claim 10 wherein saidhook comprises a slide block, said tube bender includes support meansconnected to said handle and having a recess slidably receiving saidslide block, and means for selectively retracting said slide block topermit placement of said tube in position in the tube bender withoutinterference by said hook slide block.
 12. The tube bender means ofclaim 10 further including means for biasing said hook to thetube-engaging position.
 13. The tube bender means of claim 10 whereinsaid hook comprises a slide block, said tube bender includes supportmeans connected to said handle and having a recess slidably receivingsaid slide block, and means for selectively retracting said slide blockto permit placement of said tube in position in the tube bender withoutinterference by said hook slide block, and means for biasing said slideblock to the tube-engaging position.
 14. The tube bender means of claim10 wherein said recess and slide block are polyhedral in cross-section.15. The tube bender means of claim 10 including means fo resilientlypositioning said hook.
 16. The tube bender means of claim 10 includingmeans permitting limited pivotal movement of the hook about an axisparallel to said mandrel axis.
 17. The tube bender of claim 1 whereinsaid hook defines a sharp rearward edge engaging the tube in thetube-holding disposition.
 18. The tube bender means of claim 10 whereinsaid hook defines a sharp rearward edge engaging the tube in thetube-holding disposition.